1. Field of the Invention
The present invention relates to a rotary impacting apparatus capable of providing high-frequency impacting force.
2. Description of the Related Art
Generally, an impacting apparatus such as a concrete breaker utilizes expansive force of compressed air or a combination of a motor and a crank mechanism for reciprocating an impacting piston in the main body. When reciprocated, the impacting piston repetitively hits a reciprocating implement supported at an end portion of the main body in an axial direction.
In the impacting apparatus of the above type, the impacting piston is forcibly reciprocated, so that the main body of the impacting apparatus will unfavorably be vibrated due to reaction from the impacting piston in motion. In addition, it is difficult to increase the frequency of reciprocation of the impacting piston due to the inertial mass of the impacting piston.
In order to overcome the above problems, the applicant of the present application has proposed a rotary impacting apparatus as shown in FIG. 5 of the accompanying drawings. The illustrated rotary impacting apparatus includes a rotor 6 which is rotatably supported by a housing 5, and a reciprocative implement 14 which is reciprocatively held by the housing 5. The reciprocative implement 14 includes an auxiliary reciprocating member 14a. The rotor 6 loosely retains an impact member 12 in oval retaining holes 11 formed in flanges 6a, 6b of the rotor 6. The flanges 6a, 6b are connected to each other via a connector 6c.
When the rotor 6 rotates about a rotation axis Ax, the impact member 12 repeatedly hits an impact receiving face 20 of the auxiliary reciprocating member 14a. As shown in FIG. 5, the impact member 12 is arranged to come into hitting contact with the impact receiving face 20 at a marginal portion of the face 20. (In FIG. 5, the hitting point is the left edge of the impact receiving face 20.) In hitting the impact receiving face 20, the impact member 12 will be rotated about a central axis Ay due to friction between the impact member 12 and the impact receiving face 20.
By being repeatedly hit, the auxiliary reciprocating member 14a (and consequently the reciprocative implement 14) is caused to reciprocate in a predetermined direction (vertical direction in FIG. 5).
The above rotary impacting apparatus has been found disadvantageous in the following point.
When the impact member 12 hits the impact receiving face 20 at the above-mentioned marginal portion, a rotating force M may be applied to the auxiliary reciprocating member 14a, as shown in FIG. 5. In such an instance, the auxiliary reciprocating member 14a will unfavorably be slanted in the housing 5, thereby failing to provide smooth reciprocative movement or even becoming stuck in the housing 5.
There may be several solutions to the above problems. One of them may be to lower the top dead center of the auxiliary reciprocating member 14a, so that the impact member 12 hits the auxiliary oscillating member 14a at an inner portion of the impact receiving face 20. Another solution may be increasing the diameter of the auxiliary oscillating member 14a.
However, the first solution is disadvantageous because the lowered auxiliary reciprocating member 14a fails to receive a sufficiently great impacting force from the impact member 12. The second solution is also disadvantageous because the overall size and weight of the rotary impacting apparatus will unduly be increased.